I would say "a euphemism." Even though euphemism starts with a vowel, it doesn't start with a vowel sound. It's as if it starts with the consonant version of "y". It's the same reason you say "a young person" instead of "an young person."

I would say it more like 'you-femism'. The 'y' sound is a consonant sound in this case, not a vowel sound if you see what I mean. The rule applies to words beginning with a 'proper' vowel sound, thus an orange, an apple. It flows better this way in speech - to say ' an euphemism' is very jerky and awkward.

Never hear of said rule. So I would go with the sensible approach and assume that the sound dictates 'a euphemism' is fine. If anyone can post a reputable link showing otherwise I'll be interested to see it.

catkind How rude! Nothing wrong with venturing an opinion. There are more grey areas than people think.